Imagerie acousto-optique dans les milieux diffusants épais : de l'amélioration technique à l'application pré-clinique ex vivo

Abstract : Spatially resolved optical imaging of biological tissues' depth is hampered by multiple scattering of light. Combining ultrasound localization with detection of scattered light, acousto-optic imaging provides a millimetric resolution by dealing with the "tagged" photons that are spectrally shifted of the ultrasound frequency and come from the acoustic focus confined area. Although the signal is weak and difficult to separate from simply scattered light, several techniques for coherent or incoherent detection exist and are able to produce high-quality images of the optical contrast through several inches thick scattering media. Acousto-optic imaging has already been tested for almost 20 years on calibrated samples mimicking the optical properties of tissues. However, it remains practically unknown in the medical community because examples of applications on actual diseases are missing. This thesis presents the latest enhancements in terms of resolution and speed to both coherent detection techniques we use which consist in digital and photorefractive holography. Moreover, we demonstrate the possibility to perform photorefractive holography without any optical reference beam on a BSO crystal at 532 nm. The implementation of a multi-modal imaging system which combines the acousto-optic technique with a commercial ultrasound imaging device highlights the complementarity of both information through ex vivo experiments carried out on mice tumors or human liver biopsies containing metastasis. Finally, tests performed on chicken breast samples show the ability of acousto-optic imaging to monitor the creation of thermal lesions caused by high intensity focused ultrasound.
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Submitted on : Tuesday, December 10, 2013 - 2:23:05 PM
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Emilie Benoit À La Guillaume. Imagerie acousto-optique dans les milieux diffusants épais : de l'amélioration technique à l'application pré-clinique ex vivo. Optique [physics.optics]. Université Pierre et Marie Curie - Paris VI, 2013. Français. ⟨pastel-00916570⟩

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